The person in question was arrested last year.
While it doesn’t clarify what it is, other than Australia’s nebulous concept of “child pornography,” but considering the fact he’s been jailed for 16 months (1.5y) - and can be out in eight months if he pays a fine for the last eight months - I’m going out on a limb and saying he most likely was jailed for drawings.
This is based on the fact that:
Those caught either importing or exporting child pornography from Australia can be sentenced to up to 10 years in prison or fined as much as $525,000 AUD.